perform excellent above the waterline. Below the waterline, from my experience, the galvanization will be gone in a few years. Once the galvanizing is gone, the plain steel in fresh water could hold out for many years but there is no telling exactly how long. For anything that you’re building that will be underwater, lean toward stainless.
If you plan to use a nailing gun, you’ll likely speed up the assembly time significantly. I recommend using a 3-inch (7.62-centimeter) hot- dip box nail that is ring-shanked or with a spiral. Be sure to blunt the tips to prevent splitting at the end of a board.
If nailing red cedar or redwood, you can expect the galvanized nail heads to turn brown from an interaction between the zinc fastener and tanning oils in the wood. It never bothered me but it might bother some people.
Though the nails hold very well, one complaint I hear about is the nail heads creeping up over time. This is more of a problem with floating docks than fixed. Wood floating docks can torque or twist from end to end as waves roll through, a little or a lot, depending on how well they were made. Prolonged torquing can cause nails to work up through their holes. The shrink and swell cycle of the boards may also contribute to this. Either you cope with the problem, appreciating the other attributes to nails, or use screws instead. Just be aware that if torquing is the culprit, it will work on the screws too. They either creep out like a nail will or fatigue and snap at the heads. You should use a heavy-enough wire, like a #10, and work on reducing the torque in the dock.
As a framing fastener, structural screws install very nicely with a variable-speed cordless impact wrench. These are available by several manufacturers in various lengths, coatings, and head types. If you haven’t used these before, don’t be surprised at how easily an 8-inch (20.32-centimeter) screw will install. As with any fastener, make sure that the manufacturer rates the product you’re looking at for the treated wood you’re using and your environment.
When considering your choice of head types available, whether for decking or framing, Phillips drives work well when going into cedar. If you’re going into a harder material, such as treated wood, either use a square or star drive. Structural screws are available in a hex drive that I’ve never stripped out, but I prefer the heads that are round or flat with a star drive as they are more hull friendly if brushed by a boat. If you experience trouble with the bits breaking, try a higher quality brand made with a harder steel. On deck screws, fluted tips are worth getting to reduce the chance of splitting the end of a board. If using conventional tips, pre-drill the ends of all deck boards since decking should be cut flush with the frame on a dock.
For mounting specialty dock hardware, joining posts with a frame, or cap boards, I recommend through bolting. Do not rely on lag bolts where through bolts can be used.
If possible, use all carriage bolts, keeping the heads to the exposed surfaces as they are hull- and skin-friendly while the hex nuts will be turned in. If the hex nut and the threaded end of a bolt must be on a surface that could be exposed to a hull or skin, countersink an area so that the nut and bolt set within.
Dock hardware should be through-bolted.
Around fresh water you should use hot-dip galvanized screws. In salt environments, I prefer stainless if it’s in the budget. I have a word of caution when using stainless bolts and nuts. They have a strong propensity to “gall” or seize together. Sometimes they seize before the nut is tight against the surface you’re fastening to. Once this happens, applying torque to the wrench will likely snap the bolt. Before putting stainless bolts and nuts together, inspect the threads for grit or imperfections. Then hand-tighten before applying torque with a hand wrench. Tightening at a slow speed prevents heat that can cause galling. An alternative to this would be to use brass or aluminum nuts on stainless bolts.
When drilling for bolts, match the hole size with the bolt diameter. Sometimes a slightly bigger hole is preferred so that the bolt fits into the hole with ease. That may be okay, but if it is on a component that will experience motion, such as a hinge for a floating dock, I recommend keeping a tight fit. Locking nuts, such as a nyloc, would be great if you could find them for galvanized bolts. Otherwise, locking washers are the “go to” but I recommend liquid thread lock and or double nutting. They add another level of protection to secure parts that experience motion, vibration, and wear. RTV silicone applied to the threads will also dampen vibration and help prevent bolts and nuts from working apart. Upon tightening bolts to wood, be sure to include flat washers where a hex head bolt or nut tightens directly against a wood surface.
Countersunk holes help to reduce contact with an abrasive bolt.
If you’re planning to use eye-bolts for hinging dock sections or holding significant loads, be sure to use load-rated, shouldered, forged eye-bolts. Eye- bolts that have been formed into shape with a rod may not do the job. Make sure you know its capacity and that it is fit for the job you’re subjecting it to.
Pipe leg dock hardware, made for holding the weight of dock sections and additional loads, use a setscrew to hold the weight onto the pipe. Sometimes a standard-grade three-bolt is used where the setscrew threads into the part. A better setscrew is one that is made for biting into the pipe. It is case-hardened and has a concave or cup- shaped tip. A ½ inch (1.27 centimeter)–diameter setscrew of this type has a holding capacity of 500 pounds (226.80 kilograms). When tightening, as the setscrew begins to press the pipe against the socket, only a quarter turn more to the right is needed to hold it securely.
1. A locking nut resists loosening due to vibration and shrinking of material.
2. A locking washer keeps tension on the nut to help prevent loosening.
3. Use flat washers where hexagonal nuts tighten against wood. Use them under hexagonal bolt heads that are in contact with wood.
4. For fixed docks that stand on pipe legs, the setscrew with “a cup point,” used with pipe leg hardware, cuts into the pipe for the best hold and adjustability.
5. Forged eye-bolt with shoulder.
6. Liquid thread lock is an alternative to a locking nut.
7. In a pinch, without locking nuts or liquid thread lock, apply a second nut onto the bolt to resist loosening.
Finally, when you think about all the projects you’ve worked on, building a new dock or rehabilitating an old one will possibly require a greater investment in fasteners than many of the other projects did. This is partly because bolts are a staple in holding the structure together along with your need for corrosion resistance. I’m not going to sugarcoat this. Fasteners are expensive, so before you run out to five different hardware stores and clean out their bins of the sizes you need, use the big shopping list to your advantage. Especially when it comes to stainless fasteners, give your favorite hometown hardware store manager some time with your list. Let him or her see what they can do. If they bring it in special for you, theoretically, they don’t need to make nearly the full markup since it doesn’t consume overhead sitting on their shelves. It will skip the shelves and go right to you.
Another place to try is a fastener company. Fasteners is what they do, often importing or dealing direct with a mill without a middleman.
There may not be one in your town, but even if it is an hour’s drive away, the savings will be worth going there. I have no doubt that if you plan this right and shop smart, you can save big. This will be most helpful if stainless is really what you need.